'\"
'\" Copyright (c) 1997 by Sun Microsystems, Inc.
'\" Contributions from Don Porter, NIST, 2004. (not subject to US copyright)
'\" Copyright (c) 2018 Nathan Coulter.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH Tcl_SaveResult 3 8.1 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_SaveInterpState, Tcl_RestoreInterpState, Tcl_DiscardInterpState,
Tcl_SaveResult, Tcl_RestoreResult, Tcl_DiscardResult \- Save and restore the
state of an an interpreter.
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
Tcl_InterpState
\fBTcl_SaveInterpState\fR(\fIinterp, status\fR)
.sp
int
\fBTcl_RestoreInterpState\fR(\fIinterp, state\fR)
.sp
\fBTcl_DiscardInterpState\fR(\fIstate\fR)
.sp
\fBTcl_SaveResult\fR(\fIinterp, savedPtr\fR)
.sp
\fBTcl_RestoreResult\fR(\fIinterp, savedPtr\fR)
.sp
\fBTcl_DiscardResult\fR(\fIsavedPtr\fR)
.SH ARGUMENTS
.AS Tcl_InterpState savedPtr
.AP Tcl_Interp *interp in
The interpreter for the operation.
.AP int status in
The return code for the state.
.AP Tcl_InterpState state in
A token for saved state.
.AP Tcl_SavedResult *savedPtr in
A pointer to storage for saved state.
.BE
.SH DESCRIPTION
.PP
These routines save the state of an interpreter before a call to a routine such
as \fBTcl_Eval\fR, and restore the state afterwards.
.PP
\fBTcl_SaveInterpState\fR saves the parts of \fIinterp\fR that comprise the
result of a script, including the resulting value, the return code passed as
\fIstatus\fR, and any options such as \fB\-errorinfo\fR and \fB\-errorcode\fR.
It returns a token for the saved state.  The interpreter result is not reset
and no interpreter state is changed.
.PP
\fBTcl_RestoreInterpState\fR restores the state indicated by \fIstate\fR and
returns the \fIstatus\fR originally passed in the corresponding call to
\fBTcl_SaveInterpState\fR.
.PP
If a saved state is not restored, \fBTcl_DiscardInterpState\fR must be called
to release it.  A token used to discard or restore state must not be used
again.
.PP
\fBTcl_SaveResult\fR, \fBTcl_RestoreResult\fR, and \fBTcl_DiscardResult\fR are
deprecated.  Instead use \fBTcl_SaveInterpState\fR,
\fBTcl_RestoreInterpState\fR, and \fBTcl_DiscardInterpState\fR, which are more
capable.
.PP
\fBTcl_SaveResult\fR moves the result of \fIinterp\fR to the location
\fIstatePtr\fR points to and returns the interpreter result to its initial
state.  It does not save options such as \fB\-errorcode\fR or
\fB\-errorinfo\fR.
.PP
\fBTcl_RestoreResult\fR clears any existing result or error in \fIinterp\fR and
moves the result from \fIstatePtr\fR back to \fIinterp\fR.  \fIstatePtr\fR is
then in an undefined state and must not be used until passed again to
\fBTcl_SaveResult\fR.
.PP
\fBTcl_DiscardResult\fR releases the state stored at \fBstatePtr\fR, which is
then in an undefined state and must not be used until passed again to
\fBTcl_SaveResult\fR.
.PP
If a saved result is not restored, \fBTcl_DiscardResult\fR must be called to
release it.
.SH KEYWORDS
result, state, interp
